1. Technical Field
The present invention relates to a light-emitting apparatus, a method of manufacturing the light-emitting apparatus, an image forming apparatus, and an electronic apparatus.
2. Related Art
As a printer using electro-photography, a line printer (image forming apparatus) is known. The line printer includes a charger, a line-shaped printer head (exposing head), a developer, a transfer unit, or other devices which are disposed in the vicinity of a circumferential surface of a photosensitive drum, that is, a to-be-exposed object. A plurality of light-emitting devices provided to the printer head selectively emit light to perform exposure, so that an electrostatic latent image is formed on the circumferential surface of the photosensitive drum charged by the charger. The electrostatic latent image is developed by using a toner supplied from the developer, so that a toner image is transferred on a paper by the transfer unit.
In an example of the light-emitting device for such a printer head, tow columns of inorganic or organic light-emitting diodes (LEDs) are disposed in a shape of zigzag. however, in such a light-emitting device, there is a problem in that it is very difficult to accurately array thousands of light-emitting points. Recently, there has been proposed an image forming apparatus having a printer head using a light-emitting array of organic electro-luminescence devices (organic EL devices), that is, the light-emitting devices, so that the light-emitting points can be accurately arrayed.
Generally, in such as printer head (exposing head) using the organic EL devices, a device formation substrate where the organic EL devices (light-emitting devices) are formed and a sealing substrate are attached though a sealing material to seal the light-emitting devices, so that the light-emitting devices are protected from external atmosphere (oxygen and moisture). However, in general, in the state that the sealing material is coated along the entire periphery (whole circumference) of the substrate in a shape of ring, the device formation substrate is attached to the sealing substrate. In this case, since an inner portion surrounded by the sealing material becomes a closed space, a pressure (internal pressure) thereof is higher than external pressure, so that it is difficult to control a gap between the sealing substrate and the device formation substrate.
In order to solve the problem, sealing methods are disclosed in JP-A-2003-243160 and JP-A-2003-243161. According to the methods, a first sealing material and a second sealing material is formed to have discontinuous portions, and when the substrates are attached to each other, these sealing materials are formed to be continuous.
However, in the aforementioned methods, at the time of attaching the substrates, the first sealing material and the second sealing material may not be sufficiently continuous, so that effective sealing performance is not obtained. Therefore, there is a problem of deterioration in light-emitting characteristics of the organic EL devices.
In order to solve the problems, there may be considered a method where the first sealing material is formed to be discontinuous by not coating a portion of the first sealing material without continuity in a shape of ring, and after the attaching of the substrates, a separate second sealing material is coated in a regions where first sealing material is not coated, thereby sealing the light-emitting devices.
However, in the method, there is a problem in that the second sealing material may not be selectively coated only in a described region.